Turning My House into a Botanical Wonderland
As the cooler months approach each year, I find my home gradually transforming into a lush, indoor oasis. What started as a few overwintering plants has spiraled into a full-blown botanical takeover – my living room has become the “Arctic Petunia Sanctuary” and the grape vine is now attempting to strangle my ceiling fan. By February, the living room is a veritable seed nursery, with every available surface covered in trays of seedlings.
This annual ritual has become such a normal part of my life that my kids think everyone lives this way. But after years of wishing for a dedicated year-round gardening space, my dream has finally come true – I now have a custom-built, four-season greenhouse that allows me to expand my indoor jungle to new heights. And let me tell you, cultivating with the sun has never been so rewarding.
Researching Passive Solar Greenhouses
Before embarking on this project, my husband and I spent a lot of time researching passive solar and Arctic greenhouse designs. There are so many fantastic resources out there, from Cooperative Extensions to university agriculture programs and even social media communities. One website that really caught my eye was Penn and Cords Garden, which has tons of great information and photos of high-altitude greenhouses.
We also found the Walden Labs website, which provides all kinds of solutions for self-reliance – including greenhouse plans and designs. And the Northern Greenhouse Research Project in the Canadian Yukon had a really informative article that helped shape our vision.
Defining Our Greenhouse Criteria
Once we had a good understanding of what makes a successful four-season greenhouse design, we sat down to establish our own specific criteria. We knew we wanted a south-facing orientation to maximize solar gain, but we also wanted the flexibility to supplement the passive heat with a radiant floor system. And of course, durability and energy efficiency were key, given the harsh Alaskan winters.
Designing and Building Our DIY Greenhouse
With our design goals in mind, we got to work on the plans. Using the specifications from the Bradford Research Center article, we calculated the optimal dimensions for our 12×28-foot greenhouse, with a 70-degree slope on the south-facing wall.
For the materials, we opted for 2×4 walls and 2×6 roof framing, all sheathed in 1/2-inch plywood on 24-inch centers. The walls and ceiling would be insulated with R-19 fiberglass batting, and the roof would be covered in metal roofing.
One key difference between our design and the Bradford project was the choice of glazing material for the south-facing wall. Instead of the standard 6-mil poly film, we decided to use more durable 16mm triple-wall polycarbonate sheeting. After speaking with several vendors, we learned that the 76% light transmission and R-2 insulation value of the 16mm panels were about the lowest we could go without negatively impacting plant growth.
Integrating Radiant Floor Heating
Another major addition to our greenhouse was the inclusion of a radiant floor heating system. While the Bradford project relied solely on passive solar heating, we wanted the option to supplement with a boiler-powered in-floor system.
To accommodate this, we excavated the greenhouse footprint to a depth of about 24 inches, lining the floor and walls with foam insulation. We then laid wire mesh on top of the insulation as an attachment point for the 1/2-inch plastic heat tubing. Using a 4-inch PVC pipe, we created a channel for the tubing to come up through the sand floor.
After backfilling the entire “box” with 2 feet of clean sand, we connected the tubing to a standard home hot water heater acting as the boiler. This allows us to maintain a consistent 80-degree temperature in the greenhouse, even on the coldest Alaskan days.
Overcoming Construction Challenges
Building the actual greenhouse structure was relatively straightforward, with a few notable exceptions. The most challenging part was standing up the 70-degree angled south-facing wall. To overcome this, we pre-built the entire wall in a large, flat area in front of the greenhouse, then used a tractor with a gin pole to lift and set it in place.
We also had to be mindful of the greenhouse’s orientation and placement to ensure it received adequate sunlight year-round. Due to the low winter sun angle in Alaska, we had to make sure the greenhouse was set back far enough from any tall trees or structures to avoid shading.
And while the 4 LED light tubes we installed on the interior benches provide a helpful supplement during the dark winter months, there still may not be enough natural light to sustain certain crops from November through February. It’s an ongoing experiment to see what we can successfully grow during those lean months.
Lessons Learned and Future Improvements
Looking back on the project, there are a few key lessons we’ve taken away that could benefit others looking to build their own solar greenhouse.
First and foremost, selecting the right south-facing location is crucial. The greenhouse needs to be positioned with minimal obstructions to capture as much of that precious winter sunlight as possible.
We also learned the hard way about the importance of having a proper air-bleeding mechanism for the radiant floor system. It took some trial and error to get the circulation and temperature regulation dialed in just right.
And while the 6-mil poly lining we added to the inside of the south wall has made a noticeable difference in greenhouse temperatures during the coldest months, we’re already considering upgrading to a more insulative glazing option for our next iteration.
Despite the occasional hiccup, I can say with certainty that cultivating with the sun in our custom greenhouse has been an absolute joy. The ability to extend our growing season, experiment with new crops, and simply revel in the lush, verdant environment has been a game-changer.
In fact, I’m willing to bet I could even get okra to full maturity in this thing. Now that would really impress the neighbors.
As for the overall cost of the project, I’d estimate we’re in it for around $650 all said and done. That includes the framing, insulation, glazing, and all the other materials needed to create our 12×16-foot oasis. Not bad for a truly custom, year-round greenhouse, if I do say so myself.
So if you’re looking to elevate your gardening game and cultivate with the power of the sun, I’d highly recommend exploring the DIY solar greenhouse route. It’s been a labor of love, but the rewards are truly endless. Happy gardening, my friends – may your crops be bountiful and your days filled with sunshine!
